Will uneven eyebrows rectify themselves after Botox into my frown lines and forehead?

I would suggest you see your provider. Yes it takes up to two weeks to have the effect of Botox peak and then it's best to evaluate what can be done to improve the symmetry. However if one area has lowered and looks bad and interferes with your upper field of vision, then your provider may consider more Botox to help lift up that side if the muscle that should be relaxed is found to be minimally affected by the Botox. But it is possible that you might have to go back a week later to continue to improve the result depending on how the rest of the Botox effect develops. 
The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice.  The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs

Well, it could go both ways. Your eyebrow asymmetry could either get worse or better after 2 weeks. All will Rectify itself however after the botox wears off. You can also speak to your treating physician about correcting the asymmetry. Good luck from New York City